The fire broke out at around 9:30 a.m. on May 31 at CTS Greenwaste Recycling. An RV storage facility sits near where the fire broke out, but no evacuations were ordered. No injuries were reported.
As of June 1, the fire is still smoldering but is under control. The National Weather Service is warning that skies may be hazy because of this.
Some people have even reported an odd smell in the air, although it hasn't been confirmed whether this is also from the burning mulch.
"We did start smelling something odd ventilating into our office within the last half hour," said NWS Phoenix on Twitter. "With the surface inversion overnight, most of the fumes and smoke should be trapped closer to the ground."
According to people who live near the fire, trees, branches and mulch that were piled as high as 20 feet were burned.
Shawn Gilleland, a spokesman with Rural Metro Fire, said crews contained the fire Wednesday, but smoke will continue to persist in the area.
"Arizona Department of Air Quality has and will continue to monitor air quality in the area," Gilleland said in a statement. "Smoke will be present for the next few days. Rural Metro Fire will continue to monitor the fire for next several days."
The cause of the fire is under investigation, but firefighters believe the fire was the result of spontaneous combustion.
The intersection of Elliot and Sossaman remains closed.
Area where the fire broke out: